This invention is discussed with particular reference to, and primarily in terms of, its usefulness in manual or automated applications to clean medical instruments, utensils or other equipment; however, its uses are not limited to these applications. In particular, the inventive compositions may be used in cleaning medical instruments or equipment, such as surgical instruments (scalpels, biopsy instruments, clamps and the like), endoscopes, proctoscopes, laparoscopes, colonoscopes, and other equipment used for medical or surgical procedures and other metal equipment and surfaces in use in the practice of medicine and/or dentistry. In addition, this invention is also intended to include instruments, equipment, hard surfaces and the like in facilities that have similar cleaning requirements, such as, for example, pharmaceutical manufacturing facilities, dairy farms, water recycling equipment, food processing, restaurants, hair salons, cosmetic treatments, veterinary practices, and any other application where cleaning of human or animal blood, protein, lipid soils, or other similar soils are required, and where there is a particular need for scale control and compatibility with soft metals in an applied cleaning composition. The inventive compositions are also useful for their destaining characteristics.
Detergents, including concentrated formulations, for use in cleaning hard surfaces, medical instruments, utensils and other metal equipment (parts, tools, vessels, surfaces) are known in the art. While medical instruments and associated equipment often require sterilization, typically, such instruments and equipment are first cleaned and scrubbed to remove soils, including but not limited to blood, lipid and protein soils, with which they have been coated during use. Instruments/ equipment cannot be sterilized while they are coated with these soils, since the soil may set as a hardened residue which is difficult to remove later. Soil also presents a barrier to sterilant penetration. Generally, instruments and equipment are either manually scrubbed (or rinsed) with, or soaked in, a detergent cleaning solution to remove the bulk of the soil from their surfaces or an automated washer may be utilized.
Alkaline cleaners are highly desirable because they promote saponification of fatty (oily) soils, which, in turn, facilitates the cleaning process. Highly alkaline cleaners are used for cleaning and sanitizing medical instruments, utensils and other equipment, hard surfaces, and manufacturing equipment, including Clean-in-Place (CIP) applications.
Alkaline cleaning compositions are well known in the art. By way of illustration only, U.S. Pat. No. 6,581,613 to Berkels et al. discloses a composition comprising 0.1-50% of a defined alkylpolyglucoside (D.P. 1.7 to 3 and an alkyl radical comprising 8 carbon atoms) and 50 to 99.9% of a concentrated alkali metal hydroxide solution, for use in breweries and dairies.
U.S. Pat. Nos. 6,274,541, 6,479,453 and 7,037,884 to Man disclose an alkaline cleaning composition comprising an alkyl or alkylaryl ethoxy carboxylate (0.1-20 wt. %), a strong chelating agent, such as NTA, EDTA, HEDTA, and DTPA, preferably EDTA (1-20 wt. %), and a source of alkalinity, preferably a combination of ammonia or ammonium hydroxide, monoethanolamine and sodium hydroxide (2-30 wt. %) stated to be especially effective for removing lime-soaps in greasy soils from hard quarry or ceramic tile.
U.S. Pat. No. 6,686,325 discloses an alkaline sensitive metal cleaning composition as a two part system, one portion being an alkaline concentrate comprising one chelant and the other portion being a corrosion inhibitor concentrate comprising a corrosion inhibitor, a second chelant, and a surfactant, combined with a threshold inhibitor/crystal modifier component to stabilize the corrosion inhibitor in a use solution comprising both portions.
H468 to Malik et al., a statutory invention record, discloses a process for cleaning a soiled hard surface by applying an alkaline cleaner comprising an alkalinity source 0.1-50 wt. % and an alkylglucoside (0.1 to 40 wt. %), which is stated to be superior to alkaline cleaning compositions comprising anionic and nonionic surfactants for hard surface cleaning. The formulation also contemplates the addition of phosphate builders and the use of water miscible solvents.
U.S. Pat. No. 6,541,442 to Johansson discloses an alkaline composition containing a high amount (up to 30 wt. %) of a nonionic alkylene oxide adduct surfactant and a hexyl glucoside as a hydrotrope, for use in cleaning hard surfaces, in a mercerization process, and to clean, desize and scour fibers and fabrics at a pH above 11. The composition also includes complexing agents, such as phosphates and NTA and EDTA.
U.S. Pat. No. 6,537,960 to Ruhr et al discloses a low-foaming surfactant blend for use in highly alkaline conditions comprising at least one C3 to C10 alkyl polyglucoside, at least one amine oxide, at least one polycarboxylated alcohol alkoxylate and at least one alcohol alkoxylate. The disclosed surfactant is stated to facilitate chlorine stability.
U.S. Pat. No. 6,581,613 discloses an alkylpolyglucoside with a high degree of oligomerization (1.7 to 3) in combination with 90 to 99.9% of a concentrated metal alkali.
U.S. Pat. No. 5,767,056 to Lenoir discloses an aqueous alkaline composition comprising an alkali metal hydroxide and an addition reaction product of an alcohol having 6-18 carbon atoms, with either propylene oxide and ethylene oxide or butylene oxide and ethylene oxide, for cleaning surfaces of fruits, vegetables, containers for food, or for chemical peeling of fruit or vegetables, metal working or cotton mercerization.
U.S. Pat. No. 4,935,065 discloses an aqueous alkaline cleaning concentrate/wash solution comprising sodium hydroxide, 2-phosphonobutane-1,2,4-tricarboxyclic acid, sodium polyacrylate, and sodium hypochlorite.
WO 02/47819 discloses an aqueous solution for carrying out the alkaline purification of synthetic resin ion exchangers comprising alkalinity contributors and sequestering agents in specific proportions.
Alkaline cleaning compositions of the prior art suffer from a number of disadvantages or drawbacks. While increased active alkali content is generally associated with improved cleaning performance, it also presents some safety hazards for workers, especially with very high alkali content. In addition, the use of highly alkaline compositions has been limited due to the instability of various components included in the compositions to enhance their properties. In particular, certain components, such as surfactants, hydrotropes, chelants, sequestrants, and other scale inhibition agents and the like, are difficult to incorporate into a highly alkaline, liquid composition, so that the final product is stable in storage for a reasonable shelf life. Highly alkaline cleaners also present compatibility problems with soft metals, such as the type used in medical instruments, utensils and other metal components and in equipment, such as automated washers and other disinfectors. While dilution of conventional concentrated cleaners to achieve a lower alkali content and improved compatibility is often recommended, dilution often results in less than optimal cleaning performance. As a result, an optimal cleaning composition, comprising components necessary to remove hard-to-clean soils effectively has been difficult to achieve.
There are other drawbacks to the use of current, commercially available alkaline cleaning products. Many detergent systems employ the use of chelating agents, such as tetrasodium ethylenediaminetetraacetate (EDTA) or nitrilotri-acetate (NTA), that are not considered totally biodegradable. NTA has also been classified as a possible carcinogen to humans (Group 2B) by the Insecticide Restrictions Action Committee (IRAC)'s working group. Further, certain components cannot be used in certain geographic areas, such as for example Europe, due to regulatory restrictions. Thus, achieving cleaning efficacy using conventional liquid detergents required the use of components that are not environmentally friendly or safe.
In addition to the above noted problems, the required volumes of traditional alkaline cleaning compositions in an instrument processing department within a hospital, or other facility where such cleaning is necessary, are typically very large. In order to achieve high efficiency in processing medical instruments, utensils and other equipment in automated cleaners, the change out of empty containers to full containers needs to be held to a minimum. As a result, traditional cleaning products are often manufactured as, and sold to, hospitals or other facilities in containers from 5 to 55 gallons.
Conventional concentrated cleaning compositions also generally require a chelant concentration of 10% or greater in order to be effective when diluted. For example, traditional detergent concentrates typically are diluted to ⅛-2 oz./gal. (in water) prior to use, resulting in a concentration of 195 ppm to 781 ppm of active chelant/inhibitor in the wash solution. This level of dilution necessitates the use of large volumes of cleaners (and hence containers) as well. The weight and bulk of containers pose an ergonomic risk to workers handling the containers, and the size of the containers occupies valuable space. It would be desirable, therefore, to achieve effective cleaning, scale control, destaining and compatibility properties using lower volumes of detergents/cleaners to minimize cost and space, while achieving the same or better results than prior art compositions, with the added advantage of being user and environmentally friendly.
Currently available cleaning products attempt to address the ergonomic and storage space issues associated with bulk cleaning products. In particular, cleaning compositions have been provided as solid bricks or blocks, or other solid forms, which must be diluted with water prior to introduction to the washing or cleaning process. An example of such a product is manufactured by Ecolab and disclosed in U.S. Pat. Nos. 5,786,320 and 6,632,291 B2. Two “bricks” of the solid formulations purportedly are equivalent to 15 gallons of comparable cleaning products. Despite some improvement in ergonomics, these solid products do not sufficiently protect medical (or other metal) instruments or automated instrument washers from corrosion caused by water and/or contaminants within the water. Notably, they do not contain sufficient amounts or types of components to prevent the formation of water hardness deposits or scale that result from using hard water (i.e., >about 100 ppm as CaCO3), on medical instruments or other metal parts or equipment, or in automated washers. In short, even currently available products designed to address ergonomic considerations cannot provide adequate chelation or scale inhibition in hard water applications.
An ideal liquid detergent composition should provide efficacious cleaning at low use dilutions, i.e., require less volume to clean effectively. A cleaning concentrate that requires less volume to achieve the same or better cleaning efficacy and provides effective scale control properties at low use dilutions is desirable from not only an ergonomic perspective but also costs. Using less of a cleaning concentrate to achieve efficient, effective cleaning and scale inhibition allows for smaller containers, less storage space, and reduces the cost of materials for each cleaning process.
As discussed above, conventional cleaning compositions achieve scale control through the use of highly alkaline (or acid) cleaners combined with chelants, sequestrants or other scale inhibitors that are not biodegradable. In addition, depending on water hardness in a particular geographic region, achieving scale inhibition using dilute solutions of concentrated cleaners and then maintaining scale inhibition throughout the cleaning process has been difficult to achieve. Typically, scale control in traditional cleaning concentrates has been and is being achieved by using a chelant for scale inhibition, such as EDTA (ethylene diamine tetra-acetic acid), NTA (nitrilotriacetic acid), and phosphonates, which inhibits calcium and magnesium scale deposits, by chemically binding to calcium or magnesium cations, usually in a one-to-one molar ratio, to form a complex, i.e., a chelate. Drew Chemical Corp., Principles of Industrial Water Treatment., 1984, pp. 80-84. In short, one molecule of the chelant combines with one or more ions of calcium, or another metal, to form a new complex. This complex prevents the calcium or magnesium cations from interacting with carbonate anions, thus preventing scale formation. Chelants also prevent metals, such as zinc, copper or iron, from depositing on an instrument or washer surface where they could cause staining or corrosion. Scale inhibitors, such as phosphates, can also be used to inhibit the crystal structure of calcium carbonate, thus preventing calcium carbonate salts from aggregating into particles large enough to precipitate.
Sequestrants also are used to control scale formation. Sequestrants work in a different manner. One sequestrant molecule may interact with many metal ions and salts. Sequestrants do not prevent the formation of calcium or magnesium carbonate. Rather, they interact with the small calcium and magnesium carbonate particles preventing them from aggregating into a hard scale deposit. The particles repel each other and remain suspended in the water, or form loose aggregates which may settle. These loose aggregates are easily rinsed away and do not form a deposit.
In addition to the specific chelants described above, other compositions have also been used to control calcium carbonate scale and steel corrosion. One example is U.S. Pat. No. 5,647,995, which discloses a method to control scale and corrosion in cooling water using an alkali metal diphosphinate salt that is formed by reacting an acetylenic compound with an alkali metal hypophosphite in the presence of a free radical source. The diphosphinate salt is further reacted to prepare diphosphonate compounds and diphosphinate containing adducts, oligomers, and polymers having control scale and corrosion inhibiting properties.
Another example is U.S. Pat. No. 5,489,666 which discloses a composition for inhibiting the formation and deposition of calcium scales in a circulating aqueous system, such as a cooling water system. The composition used to treat the water is a modified poly-epoxysuccinic acid, which is stated to be effective at conditions of high pH, high calcium concentration and high M-alkalinity, where conventional treatments lose efficacy.
U.S. 2005/0247637 A1 discloses a water treatment for scale control in hard water, which can be used in boilers, or other heating units, hot pipes for commercial, industrial and domestic uses, particularly for drinking water treatment, food service vending and dispensing machines with internal mixing surfaces, boiler or on demand heating elements and similar components. The treatment comprises the combination of metal particulates, e.g., zinc and copper, along with polyphosphates, which is stated to drastically reduce the scale deposition on internal surfaces of high cycle food or beverage dispensing systems with a synergistic effect compared to use of the components alone.
EP 0733073 (WO 95/15984) discloses a carboxymethyl inulin having degrees of substitution (D.S.) ranging from 0.15 to 2.5, which is stated to be useful as an inhibitor of the crystallization of calcium carbonate and is biodegradable. No specific cleaning formulations are disclosed.
Many of the traditional chelants, sequestrants and other scale control agents, including several discussed above, have been the subject of increased regulatory scrutiny due to their impact on the environment. As regulations, both international and domestic, become more stringent, the need to replace phosphorous containing chemistries is necessary. Hence, consumer preference and demand for phosphate-free chemistries is expected to increase.
Based on the foregoing, currently available concentrated alkaline cleaners present many disadvantages in their use. Many contain components that are not biodegradable or user or environmentally friendly, but are subject to strict environmental scrutiny, and thus present health and safety concerns for workers. Highly alkaline cleaners that require large volumes in use also present safety hazards for workers. Large volumes are often required to be on site and for efficiency in operations, large containers are often used for detergent supply. These large containers occupy valuable space and present ergonomic risks due to the bulk and weight of the product containers. None of the conventional alkaline cleaners achieves scale control/inhibition at lower use concentrations nor do they maintain scale inhibition throughout the cleaning process. Many of the conventional alkaline cleaners are also incompatible with soft metals at the required use concentrations.
A new, ultra-concentrated alkaline detergent composition comprising a synergistic combination of scale control components (chelants, sequestrants), has been discovered, which surprisingly combines the properties of effective soil removal, biodegradability, and scale control in one concentrated formulation. The composition provides effective scale control when used in much lower concentrations, i.e., ranging from 1/40 oz./gal. to 1/10 oz./gal., than concentrations required by traditional cleaners. The inventive compositions are also physically stable, which allows for storage of smaller volume containers.
A primary advantage of the inventive composition is the reduction in costs of processing and ergonomic risk and storage space due to its highly concentrated nature and the low use dilutions required. Even at use dilutions of 1/10 to 1/40 the amount of traditional cleaners, the inventive composition(s) provides efficacious cleaning, while controlling water hardness at least as well as that achieved with traditional chemistries and even in exceptionally hard water.
Finally, another advantage of the inventive compositions is that they provide an alternative to the use of high volumes associated with traditional alkaline cleaners and are a viable option for consumers who prefer or require alkaline cleaning chemistries without the disadvantages associated with traditional products.
Generally, the concentrated alkaline biodegradable cleaner of the invention comprises the following components:
a) two or more chelants and scale inhibitors;
b) a hydrotrope;
c) a source of alkalinity; and
d) water.
Other components may be added as well, however, effective cleaning can be achieved without the need for additional detergents or surfactants, and unexpected compatibility with soft metals is achieved even without the addition of corrosion inhibitors.
It is an object of this invention to provide an ultra-concentrated, alkaline cleaning composition for use in cleaning medical instruments, utensils and other equipment and hard surfaces, which has superior cleaning efficacy at lower alkalinity levels and avoids the above discussed disadvantages of the conventional compositions, thus providing a commercial, cost effective alternative to conventional alkaline cleaning compositions.
It is a further object of this invention to provide a phosphate-free, ultra-concentrated, alkaline cleaning composition having lower alkalinity content that is safer to handle and use and is environmentally friendly.
Yet a further object of this invention is to provide, in an ultra-concentrated, alkaline cleaning composition, which maintains its desired property of scale control inhibition even as the concentrated cleaning composition is diluted and used.
A further object of this invention is to provide an ultra-concentrated, alkaline cleaning composition, which requires less of the concentrate to be diluted to achieve the above advantages thus reducing costs.
A further object of this invention is to provide an ultra-concentrated alkaline cleaning composition, which requires less of the concentrate to achieve the same effectiveness as traditional cleaners, thus reducing the need for large volume containers to store the cleaning composition supply and the space needed to store the supply of cleaning concentrate.